Amid the chain fusion reaction and unhindered bombardment of particles, the Sun has entered its 25th cycle as scientists continue there study of the biggest star in the solar system. NASA and the National Oceanic and Atmospheric Administration (NOAA) on Tuesday declared the cosmic development and discussed how the event will affect lives on Earth.

The announcement was made by the Solar Cycle 25 Prediction Panel, an international group of experts co-sponsored by NASA and NOAA that meets once in a decade to collate studies and predict the new phase. Experts said that the Sun entered its new cycle in December 2019 transiting to a Solar Minimum, a period when the sun is least active.

Solar cycle 24 lasted for 11 years and had the fourth-smallest intensity since regular record-keeping began with Solar Cycle 1 in 1755. It was also the weakest cycle in 100 years.

“As we emerge from solar minimum and approach Cycle 25’s maximum, it is important to remember solar activity never stops; it changes form as the pendulum swings,” said solar scientist Lika Guhathakurta during the virtual panel discussion.

Solar minimum - the period when the sun is least active - as seen by the Solar Ultraviolet Imager aboard GOES-East on Dec. 15, 2019. (NOAA)

According to observations and studies, for the past eight months, activity on the sun has steadily increased, indicating a transitioned to Solar Cycle 25. Solar Cycle 25 is forecast to be a fairly weak cycle, the same strength as cycle 24 and maximum is expected in July 2025.

Meanwhile, the panel has high confidence that Solar Cycle 25 will break the trend of weakening solar activity seen over the past four cycles. “We predict the decline in solar cycle amplitude, seen from cycles 21 through 24, has come to an end,” said Dr Lisa Upton, panel co-chair and a solar physicist with Space Systems Research Corp.

However, scientists predicted, “violent eruptions from the Sun can occur at any time.”

Determining solar cycles

To determine the start of a new solar cycle, the prediction panel consulted monthly data on sunspots from the World Data Center for the Sunspot Index and Long-term Solar Observations, located at the Royal Observatory of Belgium in Brussels, which tracks sunspots and pinpoints the solar cycle’s highs and lows. Sunspots are dark blotches that arise from strong magnetic activity on the Sun. Sunspots correspond with the Sun’s natural 11-year cycle, in which the Sun shifts from relatively calm to stormy. At its most active, called solar maximum, the Sun is freckled with sunspots and its magnetic poles reverse.

The closest image of Sun snapped by Solar Orbiter. (Source: ESA)

Apart from sunspots, scientists also track the magnetic field on the giant star and cosmic rays from exploded stars in distant galaxies, that is higher during solar minimum, to predict the cycle. Another area of solar study, called helioseismology, involves scientists collecting soundwaves from inside the Sun, as a way of probing the elusive dynamo.

Deep inside the Sun, electrified gases flow in currents that generate the Sun’s magnetic field, which fuels its mighty outbursts. During solar minimum, the Sun’s magnetic field is relaxed. At the height of the solar cycle, it’s a tangled mess of magnetic field lines. Understanding this flow, called the dynamo, is key in the effort to predict what the Sun will do next.

Criticality of predicting the solar cycle

Solar cycle predictions hold significance as it gives a rough idea of the frequency of space weather storms of all types, from radio blackouts to geomagnetic storms and solar radiation storms. It is used by many industries to gauge the potential impact of space weather on operations. The prediction becomes critical with countries pushing the envelope for space explorations with US, China, India, Russia engaged in a race to Mars.

The Extreme Ultraviolet Imager (EUI) on ESA’s Solar Orbiter spacecraft took these images on 30 May 2020. (Source: ESA)

In a statement, NASA said, "Surveying this space environment is the first step to understanding and mitigating astronaut exposure to space radiation. The first two science investigations to be conducted from the Gateway will study space weather and monitor the radiation environment. Scientists are working on predictive models so they too can one day forecast space weather much like meteorologists forecast weather on Earth."